There is a relatively long history, particularly in Europe, of the clinical use of color in eye disease detection, diagnosis and management. This paper briefly traces our labs research steps involving color adaptation to isolate S cone activity in both normal and diseased eyes. Some of this early work lead most directly to today's commonly used S-cone automated visual field testing (known as SWAP) for management of glaucoma. We have also shown that S-cone pathway sensitivity loss is common for foveal measures in diabetes; it not only appears prior to visible retinal damage (retinopathy) but also fluctuates with moment to moment blood glucose levels and episodes and remissions of retinal function. We have demonstrated sensitivity loss both psychophysically and with evoked cortical potentials.

The S-cone pathway measure, when applied across the visual field, is a candidate marker for future more severe loss of retinal function in diabetes. Such markers are potentially powerful tools in the development of preventative pharmacological treatments of retinal complications of diabetes. This paper will report on our ongoing longitudinal study with patients with diabetes. Our study compares the functional losses seen across the retina for both S cone pathway function, using SWAP, and multifocal ERG (mfERG) implicit times. In a group of diabetics with little or no retinopathy these tests both show between 20% and 40% abnormalities across the visual field; the results suggest that these two measures can be separately altered in the very earliest stages of retinal function loss; by the time retinopathy appears to the clinician via fundus photos these losses are already commonly overlapping in retinal areas.